ISO C的main的退出

Illidan

“If the return type of the main function is a type compatible with int, a return from the initial call to the main function is equivalent to calling the exit function with the value
returned by the main function as its argument; reaching the } that terminates the
main function returns a value of 0. If the return type is not compatible with int, the
termination status returned to the host environment is unspecified.”
5.1.2.2.3  Program termination, ISO/IEC 9899:1999(E)

这段话比较拗口，对于main的退出，return 0; 这句是可选还是必须的？ :ask

口天草芳

从上面的话看return 0;并不是必须的。当main的返回类型是兼容与int时，如果你没有明确写出return语句那么当程序执行到}，也就是正常结束时它会返回一个0值。如果返回类型不兼容int那么这种情况是未定义的。